Thermal bridge for molding machine

ABSTRACT

A thermal bridge for an electrically heated compound molding machine wherein the heat transfer from the molding plug is reflected to a heating assembly through a thermal transfer element or thermal plug. The thermal plug is made of a highly conductive material so that small swings of the die are rapidly reflected to the heating element.

United States Patent 1 1 1111 3,767,892

Armstrong et al. 1 1 Oct. 23, I973 THERMAL BRIDGE FOR MOLDING MACHINE[56] References Cited [75] Inventors: Thaddeus J. Armstrong, ElmwoodUNITED STATES PATENTS P k; J n Ohlhaver, Deerfield, 2,701,926 2 1955Meyer 219/243 x both of 111. 3,624,836 11 1971 Rohdin 3,286,077 11/1966Radford et al 219/251 [73] Assignee: Continental Can Company, Inc.,

New York Primary Examiner-C. L. Albritton [22] Filed: July 29, 1971AttorneyAmericus Mitchell et al. [211 Appl. No.1 167,285

Related US. Application Data [62] Division of Ser, No. 809,898, March24, 1969, Pat.

[57] ABSTRACT A thermal bridge for an electrically heated compoundmolding machine wherein the heat transfer from the molding plug isreflected to a heating assembly through a thermal transfer element orthermal plug.

[2%] USP/243045154133 The thermal plug is made ofa highly Conductivemate g i 251 g rial so that small swings of the die are rapidlyreflected t m h r 1 t. 93/DlG.l;249/59; 338/23,24; 425/809, 0 eeamgeeme" 407, 143, 144; 165/26; 156/583; 100/93 P 1 laim 12 Dr wingFigures I I6 [I i I v2] 22 I v18 2 I I 1 I l 1 t: 1: 11:1 H ll i 1 1| I[Hill I 11111111111111 X] l4 f 7 l oo "In. L HI Jul PAIENIEnncI 23 msSHEET 10F 5 IN VE N TORS THA DDE U ARMSTRONG OHLHAVER I N VENTORSTHADDEUS J. ARMSTRONG JON OHLHA VER PATENTEDBBIZBISH 3.767.892 sum w sINVENTORS THADDEUS J ARMSTRONG JON OHLHAVER BY r Q410-NM ATTYPAIENIEDucrzamn 3.761.892

sum SUF 5 I NVENTORS THADDEUS J. ARMSTRONG JONOHLHAVER BY ATT').

1 THERMAL BRIDGE FOR MOLDING MACHINE This case is a divisionalapplication of US. Ser. No. 809,898, filed Mar. 24, 1969, now US. Pat.No. 3,635,6l 9, in the names of Thaddeus J. Armstrong and Jon Ohlhaver,entitled Electrically Heated Compound Molding Machine, and assigned tothe same assignee as this invention.

This apparatus is essentially an improvement of the apparatus embodiedin the patent application entitled Machine for In-Place Molding of CapGaskets, by Norbert L. Wright, US. Pat. No. 3,407,442, and assigned tothe assignee of the present invention.

This invention relates to the forming or molding of plastic materials,and more particularly, to improvements in a heated molding machine forin-place molding of resin compositions. The improvement is the use of aparticular thermal bridge between the heated die member and a heatsensitive control element.

It is a general object of the present invention to simplify and improvethe construction and operation of the machine referred to in the abovepatent.

It is another object of the invention to provide a machine having fewerelements.

It is another object of the invention to provide a machine having aquick start-up time.

It is another object of the invention to provide a machine havingexcellent heat-transfer characteristics and responsive heat control.

It is a final object of our invention to provide a machine having easierdisassembly and access for repair.

These and other objects and advantages of the invention will becomeapparent from a consideration of the molding machine which is shown byway of illustration in the accompanying drawings and more clearlyunderstood by reference to the following detailed description wherein:

FIG. 1 is a plan view of our machine for molding cap liners havingportions of the machine broken away for a clearer view.

FIG. 2 is a side elevation of our machine with portions broken away.

FIG. 3 is a partial vertical section to an enlarged scale of an upperand lower clamp member taken from the opposite side as FIG. 2.

FIG. 4 shows a part of our machine showing the ring support member.

FIG. 5 shows an upper heater element.

FIG. 6 shows a lower heater element.

FIG. 7 shows a top view of the ring support member.

FIG. 8 is a sectional view of an upper clamp member at the thermalcontrol station on the periphery of the turret.

FIG. 9 is an exploded perspective view showing the upper molding diesupport plug and clamp member.

FIG. 10 shows the thermocouple tip andthermocouple support element.

FIG. 11 shows the fragmentary section to an enlarged scale through theskirt of a cap shell prior to the molding operation.

FIG. 12 is a view similar to FIG. 11 after the molding operation and theplastic is in its final position.

As described in the accompanying figures, this device is, in mostessentials, very similar in its operation and structure to the devicereferred to in the abovementioned patent to Norbert L. Wright, US. Pat.No. 3,407,442.

FIG. 1 shows the upper heating ring 1 underneath the turret 2. Thisupper electrical heater ring is attached to the turret and rotates withthe turret. An appropriate number of slip rings are mounted on the axisof the turret and cooperating rings. In this way, power is supplied tothe electric heater. The cover 3 is shown surrounding aboutthree-fourths of the turret 2 which rotates inside the cover 3. Part ofthe turret is broken away to show caps 4 being passed into and out ofthe turret. These caps 4 are fed from a wheel pocket 5 in the wheelturret 6 and after having been processed, are taken away by anotherwheel turret 7 for further operations. The spindle operating elements ofthe individual stations of the turret are lubricated by a pump 8 showninteriorly of the turret and oil is conducted through a lubricant supplyline 9 to the necessary points on the turret. A belt 10 or similarconveyance brings unprocessed caps 11 to the machine and takes theprocessed caps 12 from the machine.

A cross-section view of the machine is shown in FIG. 2. A cross-sectionof one of the stations 13 in side elevation shows most of the movingparts. The turret 2 is rotatably mounted on a shaft 14 which extendsfrom the center of the base machine 15 upwardly. The turret has a shapesomewhat similar to a bowl having a lip 16 around its upper rim.

Suspended from the upper lip 16 is shown a crosssection of the upperheater ring 1 which is hung beneath the outer sectoin of the turret. Theheater ring 1 extends completely around the turret 2 and the temperatureof the heater ring is controlled by the amount, of electricity fed intothe ring in response to the temperature of the upper molding die 17 andto a lesser extent, the cap and lower clamping place member 18. Twopairs of heater elements 19, 20 extend completely around the ring. Theseheaterelements are connected to an external power source through sliprings. The amount of electricity conducted to and through the electricheater is controlled by thermostat which responds to the level of thetemperature in the molding die or punch 21. When the temperature of thethermostat is above a certain level, the thermostat stops the flow ofelectricity to the upper heater ring 1 and when the temperature of thethermostat is below a certain level, the thermostat starts the flow ofelectricity to heat the upper heater ring 1 until the thermostat cut-offworks as described above.

A thermostat, not shown, regulates the temperature of the lower clampinglifting member to about the same temperature as the punch. This assemblyradiates heat to the lower clamp assembly, thereby keeping it at atemperature near the curing point of the plastic being used in the caps.

As shown in the drawing, the entire area may be covered by a shield 22to protect against flying debris, dust and air currents.

Turning now to a closer view of the upper and lower punch assemblies17,18, from a different view, FIG. 3 shows the lower punch assembly 18and an upper punch assembly 17 having a single compression spring 23with two paired pins 24, 25 slidable between the punch assemblies 17,18to keep proper orientation and distance between the assemblies so thatthe punch assembly or die punch 26 enters the cap at a proper place topress down the plastic material located around the inside of the cap.The compression spring 23 imparts an upward force to the upper heattransfer element 27.

Above the die or punch 26 is shown the upper thermal transfer element 27which operates as a heat sink since it is of a much more dense materialthan the heater ring 1. In this way, as heat is extracted from the dieor punch and passed into the ambient atmosphere and the plastic materialand the cap material, this heat will momentarily lower the temperatureof the die or punch 26 somewhat which acts as a heat-removing means, butwhatever heat is lost is quickly restored by the upper thermal transferelement 27 which has a high heat capacity. The rate of heat flow throughthe upper thermal heat transfer element 27 is relatively slow incomparison to the rate of heat transferred through the heater ring 1.The heater ring is made of a material having a high heat transfercapacity, such as aluminum. In this way, when electric potential isapplied to the resistors 19,20 in the heater ring, the temperature ofthe resistors will rise rapidly and this heat is transmitted to the ringmaterial. The ring is made of a material having a high rate of heatconductivity, such as aluminum. From the heater ring, heat is passedinto the upper thermal transfer element.

The upper thermal transfer element 27 is made of a material having thecharacteristics of high heat capac-. ity per cubic centimeter and arelatively low rate of heat conductivity, for example, steel. Because ofthese two characteristics, it acts as a heat sink or thermal storageplace. The heat sink provides a buffer and a heat-equalizing region sothat the heat supplied by the heater ring on one side and the heatflowing out of the punch onthe other side do not cause wide swings inthe overall temperature of the upper punch assembly. Heat travels aboutsix times as fast in aluminum as in the upper steel heat transferelement.

The lower forming assembly is controlled in about the same manner as theupper assembly in that one or more thermostats are located around itsperiphery and as the upper turret turns, the lower assembly is heated byheater elements located in the lower heater assembly 28. A thermostat(not shown) located at the lower assembly calls for more or less heat asthe situation demands, and keeps the lower assembly within a temperaturerange of to of about 425 F, depending on the plastic heat curablematerial used for the gasket.

Shown in FIG. 4 is a plan view of details of the heater support ring 29found in FIGS. 1 to 3, inclusive. This support ring 29 has diagonalslots 30 in it so that the lower heater supporting elements 31 (FIGS. 2and 3) are mounted in these diagonal slots 30 and may be moved from aposition of about l/l6 inch away from the lower die or punch assembly toseveral inches away. This slot arrangement facilitates repair work ofthe turret and lower support structure because when the lower heatingring 28.is moved backward several inches, access to the lower structureis more readily possible. The supporting means 29 is mounted on posts32. In order to render access to the interior of the machine even moreeasy, the posts on each side are ofa simple snapin removable typesupport. When one or two of these supports are removed, the heatersupport ring is then held up by the other four or five supports shown inthe figures. These four rear-most supports are fastened top and bottomso that elimination of any one support is not fatal to the function ofthe ring.

The upper heating ring 1 is shown in perspective view in FIG. 5.Terminals for conducting electricity into and out of the heater ring 1are connected so that the two pairs of inner terminals 33,34 connect tothe resistors shown to the inside of the ring. The two pairs of outerterminals 35,36 connect to the outer resistors 20. As shown best inFIGS. 3 and 5, the electric terminals conduct electricity into theresistor elements 19,20 cast into the aluminum ring 1. The thermal rateof conductivity of aluminum is quite high. The aluminum heater ring 1conducts heat from the resistors quite rapidly. Passages 37 shown in theheat ring pass completely through the ring to accomodate the shafts 38of the molding elements (FIG. 3). The heater elements 19,20 pass insideor outside of the passages 37.

A pair of lower heating elements 28 are mounted about the lower punchassembly 18. One of the two lower heaters 28 is shown in FIG. 6. Severalresistor elements 39 conduct electricity and develop heat. Behind theresistor elements are heat reflectors 40 to divert any heat rays forwardtoward the lower assembly. While the heat radiated by these heaterelements 28 is of considerable criticality in the forming of the plasticring, it is not quite as critical as the amount of heat developed in theheater ring because the upper die or punch is in physical contact withthe plastic ring and therefore, the heat imparted to the plastic orplastic disc 41 (FIG. 12) from the upper die or critical punch 26 is ofmore consequence to its forming.

FIG. 7 shows the support ring 29 itself as it is seen withoutanyfastenings. On the right and left are paired slots 30 for supporting thelower heating semi-circular elements 28 so that these elements can bemoved into and out of proximity with the lower heated die assembly 18.When the lower heater is moved forward in the slots, it is about l/l6inch from the lower die assembly.

' In an apparatus of this sort, the level of the temperature of theupper and lower dies is critical. If the temperature of the die is toohigh, the plastic inside the cap will burn and stick to the punch. If,on the other hand, the temperature of the die is not high enough, theplastic material will not flow to form the desired sealing contact allthe way around the cap (FIGS. 11 and 12). A temperature range at whichthe plastic will work satisfactorily is on the order of 410 to 425 F.Some plastic materials may be cured in a broad range of temperatures,such as 300 to 500 F. In the usual factory operating conditions, avariety of influences play upon a machine. For example, it may besummer, winter, raining, high humidity, low humidity, or drafty. Each ofthese variable atmospheric conditions affects the rate at which heatflows from the machine'and thus affects heat distribution through themachine. It is necessary for the heat to be at'a very precise level oftemperature at the point where the die 26 or punch forms the plastic inthe cap. Since the various atmospheric effects play upon each station ofthe turret with approximately the same result at each station, a verygood control can be accomplished by having one thermal control pointat'a single upper punch assembly 26 on the periphery of the turret 2.Such a thermal control point is established at the station shown incross-section in FIG. 8. The heater ring 1 with its paired resistanceelements is mounted to the top element 42 (FIG. 3) shown and below thatand pressed into contact with it is the upper thermal transfer element27 which forms a heat sink. Shown on the left-hand side of the upperthermal transfer element 27 is a plug 42 extending through the upperthermal transfer element. This plug is made of a material having a highthermal conductivity and acts as a thermal conducting means. Aperspective view of the upper thermal transfer element 27, the punch 26,the thermal plug 42, and the locator pins 24,25 is shown in FIG. 9.

The details of the thermal plug and the thermocouple combination areshown in FIG. 10. The plug 42 is shown before it is driven into theupper element 27 in FIG. 8.

While it is out of the assembly, the thermocouple 45 is pushed down intothe plug 42 where it snaps into place. The plug has slits 44 almost halfof its length in four perpendicular directions. This facilitates latercrimping of the plug when it is forced into the upper thermal transferelement 27. When the thermal plug 43 has been driven into the thermalelement, the themocouple 45 is located fairly close to the die or punch26. ln this way, temperature gains or looses of the die or punch arereflected into the heater ring much more quickly than would be the caseif the thermal plug was of a material which conducted heat slowly. Theamount of heat added to the heater ring in order to bring the die orpunch up to the given temperature is lessened. Thus, heater plug 43 is athermal connection between the heater ring and the die or punch so thatthe extent of the temperature swings of the die or punch areconsiderably lessened by means of the thermally conductive bridge formedby the thermal plug.

The method of forming the thermal plug with included thermocouple is ofparticular interest. The thermal plug 42 is made of a highly conductivematerial in the form of a cylindrical plug having a channel 46 throughits center. The plug is flat at its ends and is slit 44 up one-third toone-half of the way, the slit being in the form of an X. Once thethermocouple 45 is inserted into the thermal plug 42, the thermal plugmay be pressed together so that the thermocouple element 45 is caught inthe bottom of the thermal plug 42. When the thermal plug is shoved upinto the thermal transfer element, it makes a tight fit which holds itin place.

The function of the upper heat transfer element 27 is two-fold. It actsas a heat sink and also since it is made of a very strong material, thefour locator pins 47 center the cap in a very precise position. If thematerial were made of other than steel or the like, a locator fingermight bend, and this would result in an immediate malfunction of themachine. Further, this element is capable of being smoothed to a highdegree and may have high contact pressure with the aluminum heater 1.Because of the density of the material in the heat sink and the slowrate of which heat flows through this material, more heat is accumulatedper cubic centimeter in the material of the heat sink than is in thealuminum heater ring. By means of having an intermediate heat sink,greater stability is assured to the temperature of the punch member.Since the heater ring may swing widely in temperature, the buffer heatsink protects the punch and consequently, the cap member from thetemperature swings of the heater ring and insures a considerably greaterstability to the plastic material and the punch which heats it.

While particular materials and specific details of construction havebeen referred to in describing the form of the machine illustrated, itwill be understood that other suitable materials and equivalentstructreal de- 6 tails may be resorted so without departing from thespirit of the invention. What is claimed is:

1. A thermal bridge for critical temperature areas comprising:

a heater means;

A heat-removing means;

a thermal transfer means having a low thermal conductivity and a highthermal capacity compared to both said heater means and saidheat-removing means for conducting heat from said heater means to saidheat-removing means to provide a thermal barrier and a heat sink betweensaid heater means and said heat-removing means;

a passageway extending at least part way through said thermal transfermeans in the direction of thermal flow through said thermal transfermeans from said heating means to said heat-removing means;

an elongated thermal conducting means having high thermal conductivitycompared to said thermal transfer means in said passageway and extendingfrom said heat-removing means toward said heating means; and

a temperature sensing element mounted inside said elongated thermalconducting means near to said heat-removing means whereby when heat isextracted from said heat-removing means to lower the temperature of saidheat-removing means, the temperature of the temperature sensitiveelement is affected in a short time and the temperature of said heatermeans may be raised to re-supply heat to sad thermal transfer means andthus to said heatremoving means.

2. A thermal bridge for critical temperature areas as set forth in claim1 in which said heater means comprises,

at least one resistance means for imparting heat to the rest of saidheating means,

a highly conductive material surrounding said resistance means andhaving one surface in intimate contact with said thermal transfer meanswhereby heat is conducted from said heating means to said thermaltransfer means.

3. A thermal bridge for critical temperature areas as set forth in claim1 in which said heat-removing means comprises,

a die element for in-place molding of a plastic cap liner.

4. A thermal bridge for critical temperature areas as set forth in claim1 in which said heat-removing means comprises,

a punch made of a heat conductive material and shaped for in-placemolding of a plastic cap liner.

5. A thermal bridge for critical temperature areas as set forth in claim1 in which said thermal transfer means comprises,

at least one plate made of a relatively dense material and adapted forintimate contact on a first side with said heating means and on a secondside with said heat-removing means.

6. A thermal bridge for critical temperature areas as set forth in claim1 in which said elongated thermal conducting means comprises,

a cylindrical member having a longitudinal axis, a

first and second somewhat flared end,

a first slot in said first flared end and extending along saidlongitudinal axis about half-way up the length of said cylindricalmember,

a second slot at right angles to said first slot and extending abouthalf-way along said longitudinal axis of said cylindrical member,

a passageway extending along the longitudinal axis of said cylindricalmember from said first end to near said second end whereby a temperaturesensitive means may be inserted to near said second end.

7. A thermal bridge for critical temperature areas as set forth in claim6 in whichsaid elongated thermal conducting means further comprises,

a slot in said first end to accommodate an electrical lead to saidtemperature sensitive means.

8. A thermal bridge for critical temperature areas as set forth in claim7 in which said thermal transfer means further comprises,

a channelway in a surface of said thermal transfer means for anelectrical lead to said temperature sensitive means.

9. A thermal bridge for critical temperature areas as set forth in claim1 in which said elongated thermal conducting means comprises,

an elongated cylindrical plug fitting snugly into said passageway insaid heat transfer means.

10. A thermal bridge for critical temperature areas as set forth inclaim 6 in which said cylindrical member comprises:

an elongated element fitting snugly into said passageway in said thermaltransfer means.

11. A thermal bridge for critical temperature areas comprising:

a heater means;

a heat-removing means;

a thermal transfer means having a high thermal capacity compared to bothsaid heater means and said heat-removing means for conducting heat fromsaid heater means to said heat-removing means;

a passageway extending at least part way through said thermal transfermeans in the direction of thermal flow through said thermal transfermeans from said heating means to said heat-removing means;

an elongated thermal conducting means having high thermal conductivitycompared to said thermal transfer means fitting snugly in saidpassageway and extending from said heat-removing means toward saidheating means; and

a temperature sensing element mounted inside said elongated thermalconducting means near to said heat-removing means whereby when heat isextracted from said heat removing means to lower the temperature of saidheat-removing means, the temperature of the temperature sensitiveelement is affected in a short time and the temperature of said heatermeans may be raised to resupply heat to said thermal transfer means andthus to said heat-removing means.

1. A thermal bridge for critical temperature areas comprising: a heatermeans; a heat-removing means; a thermal transfer means having a lowthermal conductivity and a high thermal capacity compared to both saidheater means and said heat-removing means for conducting heat from saidheater means to said heat-removing means to provide a thermal barrierand a heat sink between said heater means and said heatremoving means; apassageway extending at least part way through said thermal transfermeans in the direction of thermal flow through said thermal transfermeans from said heating means to said heatremoving means; an elongatedthermal conducting means having high thermal conductivity compared tosaid thermal transfer means in said passageway and extending from saidheat-removing means toward said heating means; and a temperature sensingelement mounted inside said elongated thermal conducting means near tosaid heat-removing means whereby when heat is extracted from saidheat-removing means to lower the temperature of said heat-removingmeans, the temperature of the temperature sensitive element is affectedin a short time and the temperature of said heater means may be raisedto re-supply heat to said thermal transfer means and thus to saidheat-removing means.
 2. A thermal bridge for critical temperature areasas set forth in claim 1 in which said heater means comprises, at leastone resistance means for imparting heat to the rest of said heatingmeans, a highly conductive material surrounding said resistance meansand having one surface in intimate contact with said thermal Transfermeans whereby heat is conducted from said heating means to said thermaltransfer means.
 3. A thermal bridge for critical temperature areas asset forth in claim 1 in which said heat-removing means comprises, a dieelement for in-place molding of a plastic cap liner.
 4. A thermal bridgefor critical temperature areas as set forth in claim 1 in which saidheat-removing means comprises, a punch made of a heat conductivematerial and shaped for in-place molding of a plastic cap liner.
 5. Athermal bridge for critical temperature areas as set forth in claim 1 inwhich said thermal transfer means comprises, at least one plate made ofa relatively dense material and adapted for intimate contact on a firstside with said heating means and on a second side with saidheat-removing means.
 6. A thermal bridge for critical temperature areasas set forth in claim 1 in which said elongated thermal conducting meanscomprises, a cylindrical member having a longitudinal axis, a first andsecond somewhat flared end, a first slot in said first flared end andextending along said longitudinal axis about half-way up the length ofsaid cylindrical member, a second slot at right angles to said firstslot and extending about half-way along said longitudinal axis of saidcylindrical member, a passageway extending along the longitudinal axisof said cylindrical member from said first end to near said second endwhereby a temperature sensitive means may be inserted to near saidsecond end.
 7. A thermal bridge for critical temperature areas as setforth in claim 6 in which said elongated thermal conducting meansfurther comprises, a slot in said first end to accommodate an electricallead to said temperature sensitive means.
 8. A thermal bridge forcritical temperature areas as set forth in claim 7 in which said thermaltransfer means further comprises, a channelway in a surface of saidthermal transfer means for an electrical lead to said temperaturesensitive means.
 9. A thermal bridge for critical temperature areas asset forth in claim 1 in which said elongated thermal conducting meanscomprises, an elongated cylindrical plug fitting snugly into saidpassageway in said heat transfer means.
 10. A thermal bridge forcritical temperature areas as set forth in claim 6 in which saidcylindrical member comprises: an elongated element fitting snugly intosaid passageway in said thermal transfer means.
 11. A thermal bridge forcritical temperature areas comprising: a heater means; a heat-removingmeans; a thermal transfer means having a high thermal capacity comparedto both said heater means and said heat-removing means for conductingheat from said heater means to said heat-removing means; a passagewayextending at least part way through said thermal transfer means in thedirection of thermal flow through said thermal transfer means from saidheating means to said heat-removing means; an elongated thermalconducting means having high thermal conductivity compared to saidthermal transfer means fitting snugly in said passageway and extendingfrom said heat-removing means toward said heating means; and atemperature sensing element mounted inside said elongated thermalconducting means near to said heat-removing means whereby when heat isextracted from said heat-removing means to lower the temperature of saidheat-removing means, the temperature of the temperature sensitiveelement is affected in a short time and the temperature of said heatermeans may be raised to resupply heat to said thermal transfer means andthus to said heat-removing means.